The present invention concerns processing of integrated circuits and pertains particularly to using a baffle boat during wafer processing.
In order to process silicon wafers in a horizontal diffusion oxidation furnace, a paddle is loaded with four production boats. Each production boat holds, for example, twenty-five wafers to be processed, and is, for example, made of quartz.
In addition, at each end of the paddle there is loaded an additional boat which function as baffle boat. Each baffle boat is also filled with twenty-five wafers. The baffle boats are used to help hold in the heat and diffuse gasses in order to give proper uniformity during atmospheric oxidation within the horizontal diffusion oxidation furnace. Generally, in each baffle boat one of the wafers is used as a monitor wafer to monitor the thickness of oxidation during the run.
One disadvantage to using baffle boats is that during any run through the horizontal diffusion oxidation furnace, fifty wafers are not used for production of parts. Rather forty-eight wafers are used to construct a baffle and two wafers are used to monitor the thickness of oxidation. This can increase processing costs.
While it is possible to reutilize the forty-eight wafers used to construct a baffle, after repeated cycles the wafers begin to warp and must be replaced.